EP0077653B1

EP0077653B1 - Device for applying foam to textiles

Info

Publication number: EP0077653B1
Application number: EP82305476A
Authority: EP
Inventors: Joseph A. Pacifici
Original assignee: Westpoint Pepperell Inc
Current assignee: Westpoint Pepperell Inc
Priority date: 1981-10-15
Filing date: 1982-10-14
Publication date: 1986-02-05
Also published as: CA1186889A; WO1983001399A1; EP0077653A1; DK248283D0; DE3268995D1; BR8207927A; DK248283A; US4667882A; JPS58501728A

Description

It is well recognized that wet processing in the textile industry is a major source of energy consumption. With the advent of high energy costs, and concern as to the availability of oil and natural gas, considerable effort has been expended in reducing energy usage forwet processing techniques such as bleaching, dyeing, printing and finishing.
A technology which has developed as a result of energy conservation research in the textile field is the use of foams for wet processing. By foaming techniques, the amount of liquid applied to the textiles is reduced substantially thereby greatly lowering the amount of energy required to dry the product. Not only is there a saving of energy, but foaming also permits increased productivity and a variety of other advantages.
Known foaming techniques generally utilize metering rolls and/or doctor blades for applying the correct amount of foam to the textile. A more complete discussion of such arrangements is presented in US-A-4,297,860. This discloses an arrangement which includes an applicator in which foam is directed to an apertured spreader plate having on its downstream side a chamber which is trapezoidal in cross section and filled with a bed of porous material. Foam passing through the porous bed exits from the applicator through an elongate discharge nozzle at the tapered end of the chamber.
The applicator disclosed in US-A-4,297,860 is capable of producing a uniform foam discharge, but it suffers the discharge of requiring a substantial amount of purge time before this is accomplished. Furthermore, the applicator is not capable of being readily altered in orientation to permit variations in the direction of foam discharge.
In US-A-4,201,321, a device comprising a pair of concentric pipes having different diameters is disclosed as being suitable for use as an applicator in a foam generating operation. A foamable liquid reaction mass supplied to the inner pipe passes through overflow apertures at the top thereof into a hollow space between the pipes from which it exits through a longitudinally extending discharge slit at the bottom of the outer pipe onto a conveyor where a sheet of foam is formed. The device is clearly not intended to be used in any other angular orientation and can only be used for discharging the foamable mass onto the top of a substantially horizontal web. In order to achieve uniform discharge of the foamable reaction mass, the inner pipe has a varying cross section produced by wedges introduced within the inner pipe. These wedges, and the provision of the inner pipe outlet apertures only at its top, lead to dead spots in the device, making it unsuitable for use with a viscous foam supplied to and passing through the device.
US-A-3,967,314 discloses a device, hereinafter referred to as of the kind described, for receiving a supply of foam and discharging the foam in a choice of directions onto a textile material, the device comprising an outer pipe provided with a longitudinally extending discharge slit, a porous material within the pipe covering the discharge slit, and an inlet for supplying foam under pressure to the interior of the pipe and hence through the porous material and out of the discharge slit. This device is intended to receive a supply of coarse, comparatively fluent, foam, and the porous material, which is exemplified as a porous plate or an insert of fabric or felt, transforms the foam into a finer, more viscous, foam, suitable for application. The use of the porous material does provide a back pressure enabling the device to be oriented so as to discharge the foam in different directions. However, the plate, or insert of fabric or felt, is comparatively thin, compared to the internal diameter of the pipe and the majority of the interior of the pipe exists as an unobstructed space. The foam, flowing into this space at one end of the pipe, will tend to stagnate within the pipe at positions generally diametrically opposite to the discharge slit. Generally foams a semi-stable and, upon stagnation, tend quickly to breakdown into liquid and air. This leads to serious inhomogeneity in the foam leaving the device with consequential potential spluttering, blockages, and streaking on the material to which the foam is applied.
In accordance with the present invention, a device of the kind described is characterised by an inner pipe concentrically arranged within the outer pipe to define an annular space therebetween and provided with a plurality of longitudinally extending slits, which are angularly spaced around the axis of the pipes relatively to one another and to the discharge slit; by the porous material filling the annular space; and by the inlet leading into the inner pipe.
With this construction, foam supplied to the inner pipe passes through its slits, and then in both directions around the annular bed of porous material, and is discharged from the slit in the outer pipe onto a textile material moved past the discharge slit. The direction of discharge can be changed merely by rotating the concentric pipe arrangement about its longitudinal axis.
The invention will be described in detail with respect to the accompanying drawings, wherein:-

Figure 1 is a cross-sectional view of a preferred embodiment of the invention; and,
Figure 2 is a sectional view taken on the line 2-2 of Figure 1.

Referring to the drawings, an inner pipe 10 is positioned in concentric relationship with respect to an outer pipe 12. The external diameter of pipe 10 is less than the internal diameter of pipe 12 so as to define a space 14 between the pipes which is filled with porous material 16. Suitable for this purpose are spherical beads formed from various substances, e.g. glass and having a diameter of approximately 3 mm.
The pipes 10 and 12 are retained concentric by end caps 18 and 20 through and beyona wnicii the inner pipe 10 projects. Suitable O- rings 22, 24, 26 and 28 seal the pipes with respect to the end caps.
The inner pipe 10 is provided with a plurality of slits 30, as can be appreciated particularly with reference to Figure 2. These slits are disposed 120° apart and extend substantially the entire length of the portion of pipe 10 between caps 18 and 20. Typically, the slits have a width of about 0.5 mm, which is substantially less than the diameter of the beads 16. Each slit 30 may be formed by a single elongate opening in pipe 10 or, alternatively, by a plurality of spaced apertures aligned along the length of the pipe.
The outer pipe 12 has a discharge slit 32 extending longitudinally of the pipe and having a length substantially the same as that of the slits 30. Slit 32 is angularly offset with respect to the slits 30.
The actual width of the discharge opening from the outer pipe 12 is determined by a pair of tapered elements 34 and 36 secured to the exterior of the pipe by screws 38 and 40. By conventional means, the opening established by the spacing between elements 34 and 36 can be varied as desired. A typical range of adjustment is from 0-3.2 mm.
The slit 32 has a width which is larger than the diameter of the beads 16. Accordingly, a screen 42 is held in place over slit 32 by elements 34 and 36 to prevent the escape of the beads.
The ends of inner pipe 10 extending beyond caps 18 and 20 are threaded to permit various connections. While it is possible for foam to be supplied to the applicator from both ends of pipe 10, it is preferred that the supply of foam be from one end only. Accordingly, a cover 44 is connected to an end of the pipe and the opposite end receives the supply of foam through an adaptor indicated generally as 46. Both the cover 44 and adaptor 46 are separated from end caps 18 and 20 by spacers 48 and 50.
In operation, foam supplied through adaptor 46 to the interior of pipe 10 passes through slits 30 into the space 14 between the pipes. The porous bed of beads 16 provides a limited amount of back pressure against the flow of foam to ensure uniform distribution of the foam as it passes through slit 32 in pipe 12 and then through the screen and the discharge opening defined by elements 34 and 36. With the movement of a textile past the discharge opening, the foam is evenly applied thereto.
By merely rotating the applicator, the direction of discharge can be altered, as desired. Furthermore, the compact structure of the applicator facilitates the use of more than one applicator in close proximity to one another. This can be advantageous, for example when it is desired to apply foam to opposite sides of a textile by separate applicators.
Although the arrangement which has been described provides a uniform foam discharge very quickly after initial introduction of the foam to the applicator, it is possible to replace the cover 44 with a diverter, such as a gate valve, to permit foam properties to be checked before it is allowed to pass through the applicator's discharge opening. Of course, such a diverter also can permit the foam to be sampled any time after start-up.
A feature of the applicator which has been described is that it can be made of different lengths for use with a variety of textiles ranging from narrow knits to wide carpets.

Claims

1. A device for receiving a supply of foam and discharging the foam in a choice of directions onto a textile material, the device comprising an outer pipe (12) provided with a longitudinally extending discharge slit (32), a porous material (16) within the pipe covering the discharge slit, and an inlet (46) for supplying foam under pressure to the interior of the pipe and hence through the porous material and out of the discharge slit; characterised by an inner pipe (10) concentrically arranged within the outer pipe (12) to define an annular space (14) therebetween and provided with a plurality of longitudinally extending slits (30), which are angularly spaced around the axis of the pipes relatively to one another and to the discharge slit (32); by the porous material (16) filling the annular space (14); and by the inlet (46) leading into the inner pipe (10).

2. A device according to claim 1, wherein the porous material comprises a bed of spherical beads (16).

3. A device according to claim 2, wherein the beads (16) have diameters which are larger than the widths of the slits (30) in the inner pipe (10), and which are smaller than the width of the slit (32) in the outer pipe (12); the beads (16) being prevented from escaping through the slit (32) by a screen (42).

4. A device according to any one of the preceding claims, wherein the discharge slit (32) directs the foam through a discharge opening defined between two elements (34, 36) projecting radially outwardly, and extending longitudinally, of the outer pipe (12), one adjacent to each side of the discharge slit.

5. A device according to claim 4, wherein the elements (34, 36) are adjustably mounted on the outer pipe (32) whereby their mutual spacing and hence the width of the discharge opening is variable.

6. A device according to any one of the preceding claims, wherein the inlet (46) leads into at least one end of the inner pipe (10).

7. A device according to any one of the preceding claims, wherein there are three of the slits (30) in the inner pipe, angularly offset from one another by 120°.

8. A device according to any one of the preceding claims, wherein the pipes (10, 12) are maintained concentric by end caps (18, 20) which are mounted on respective ends of the outer pipe (12) and through which ends of the inner pipe (10) project.

9. A device according to any one of the preceding claims, wherein the slits (30) in the inner pipe and the discharge slit (32) extend for substantially the entire length of the annular space (14).